Matrix Orbital GLK12232-25-FGW - Manual (Page 20)

* to be able to read the replies of query commands (eg. cmds 54, 55) the following command must be
sent (only needs to be sent once, so this can be done somewhere in init): 254 / 160 / 0 this command puts
the reply data in the I2C output buffer instead of the RS232 output buffer. Please note that due to a 16 byte
output buffer, query commands that reply with more than 16 bytes cannot be read (eg cmd Get FileSystem
Directory)
* 3ms delay between the read commands
* 625us delay in between data bytes within a transaction is necessary
* 375us between transactions is necessary
Because of the considerable amount of delays necessary for I2C, it is suggested that the users explore
the possibility of using other built in graphic commands to clear areas of the display when refreshing all or
part of the display. For example, instead of sending the clear screen command, consider sending a rectangle
command with the proper size, this is much faster than clearing everything and re-drawing or writing spaces
over the area.
4.1.2 Serial Communication
In addition to being able to communicate via I 2 C the GLK12232-25 communicates natively through the
RS-232 protocol at at a default baud rate of 19,200 bps and is capable of standard baud rates from 9600 to
115,200 bps. Furthermore the GLK12232-25 is also capable of reproducing any non-standard baud rate in
between using values entered into our baud rate generation algorithm and set through command 164 (0xA4).
The display module communicates at standard voltage levels of ±30V to ±30V or at TTL levels of 0 to +5V
by setting the Protocol Select Jumpers to TTL.
4.2 Turn Flow Control On
Syntax Hexadecimal 0xFE 0x3A [full] [empty]
Decimal 254 58 [full] [empty]
ASCII 254 “:” [full] [empty]
Parameters Parameter Length Description
full 1 Bytes remaining before issuing a
almost full message. (Full is 0)
empty 1 Bytes available before issuing a
almost empty message. (Empty is
128)
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